Fluid-pressure system.



G. E. LORD.

FLUID PRESSURE SYSTEM.

APPLICATION FILED SEPT. 24, 1900.

Patefited Sept. 13,1910.

w M 1m UNITED STATES PATENT OFFICE.

CHARLES E. LORD, OF NORWOOD, OHIO, ASSIGNOR TO ALLIS-CHALMERS COMPANY, A

CORPORATION OF NEW JERSEY.

FLUID-PRESSURE SYSTEM.

Application filed September 24, 1906. Serial No. 836,023.

To all whom it may concern:

Be it known that I, CHARLES E. Lonn, a citizen of the United States, residing at Norwood, in the county of Hamilton and State of Ohio, have invented certain new and useful Improvements in Fluid-Pressure Systems, of which the following is a full, clear, and exact specification.

My invention relates to motor-driven fluid pumps and especially to unloading means therefor.

In starting fluid pumps such as air compressors a heavy load is placed on the driving motor unless some special means is used for preventing it.

My present invention has for its,0bject the production of an unloading means for electrically driven pum s which shall be simple and inexpensive ut withal reliable.

To this end my invention comprises the ,cmnbination of a motor-driven pump, means for normally unloading said pump, and means for gradually rendering said unloading means inoperative after the pump is started.

Other features of my invention will appear hereinafter.

The single figure of the drawing shows one embodiment of my invention.

The motor 10 which may be of any desired type is supplied from any source of current such as a trolley wire 12, as my invention is particularly applicable to air compressors for air-brake systems. The motor 10 drives an air-compressor or other fluid pump 13 which supplies a reservoir 14 through a" pipe 15. From the reservoir 14 the com ressed air or other fluid may be drawn tlirough a pipe 16 for any desired purpose. A pressure switch 17 is connected to the reservoir 14 and is arranged to close the motor circuit upon decrease of pressure and open it upon increase of pressure. This pressure switch per 86 forms no part of my present invention and may be of any desired form.

In the pipe 15 is a relief valve 18 which is normally 0 en and connects the pipe 15 to the atmosp ere or other source of fluid su ply. This relief valve 18 is arranged to e closed by a solenoid 19 in the motor (3111311113 and energized when the motor circult 1s completed. A dash-pot 20 retards the closing movement only of the relief valve 18. In the pipe 15 between the reservoir 14 and the relief valve 18 is a check valve 21 to prevent the backward flow of the fluid from the reservoir 14. This is especially necessary when the valve 18 is open.

The operation of the system is as follows: When the pressure of the reservoir decreases below normal the pressure switch 17 closes and completes the circuit of the motor 10 and the solenoid 19. The motor immediately starts and drives the compressor 13, but the compressor carries no load as it discharges to the atmosphere or other source of fluid supply through the open valve 18. The solenoid 19 is also energized and at once begins to close the relief'valve 18, but is retarded in this by the dash-pot 20. The opening of the valve 18 through which the compressor 13 discharges to the atmos here is thus gradually reduced and finally c osed. This causes the compressor to discharge a gradually increasing amount of air into the reservoir 14 and gradually increases the load on the compressor 13. The dash- 0t 20 may be so constructed that the closing of the valve 18-docs not take lace until the motor 10 has reached practically its full speed. The compressor continues to supply air to the reservoir until the pressure in the reservoir 14 has again reached or slightly exceeded the normal, when the switch 17 is opened and the circuits of the motor 10 and solenoid 19 are broken. This allows the motor to stop and the valve 18 to open quickly. The check valve 21 prevents the reservoir 14 from discharging to the atmosphere through the valve 18. As the air from the reservoir 14 is drawn out through the pipe 16 or otherwise, the above cycle 1s repeated and maintains the ressure in the reservoir 13 constant wit in the limits for which the switch 17 is set.

Various modifications in the structure herein set forth ma be made without departing from the spirit and scope of my invention and all such I aim to cover in-the appended claims.

What I claim is 1. A fluid pressure system, comprising a pump, an electric motor for drivin said pump, a pressure switch controllin t e motor circuit, a reservoir supplie by the pump, a valve between the pump and the reservoir normally open to the source of fluid supply, an electromagnet for closing said valve, and means for retarding such closure.

2. A fluid pressure system, comprising a pump, an electric motor for driving said pump, a reservoir supplied by the ump, aswitch controlling the motor circuit in re-.

sponse to variations in pressure of the fluid in the reservoir, and a slow-closing valve between the reservoir and the pump whlch is normally open to the source of fluid supply.

3. A fluid pressure system, comprising a motor-driven pump, a reservoir supplied by the pump, a normally open relief valve between the pump and the reservoir, and means for closing said valve gradually.

4. A fluid pressure system comprising a reservoir,a motor-driven air compressor sup plying the reservoir, a switch in the motor circuit responsive to the pressure in the reservoir, a slow-closing relief valve between the compressor and the reservoir, and an electromagnet controlled by said switch for closing said relief valve.

5. A fluid pressure system comprising a reservoir,a motor-driven air compressor supplying the reservoir, a relief valve between the compressor and the reservoir, a solenoid for closing said valve, and a dash-pot for and means for gradually rendering said unloading means inoperative after the pump has started.

8. In combination, a reservoir, {j motordriven air compressor supplying the reservoir, a normally open relief valve between the compressor and the reservoir, and means for slowly closing said relief valve.

9. An unloading device for air compressors comprising a normally open valve, an electroma net for closing said valve, and a dash-pot or retardingsuch closure.

10. An unloading device for air compressors, comprising a normally open valve, means for closing said valve, and means for retarding such closure.

11. A fluid pressure system comprising a reservoir, a pump sup lying said reservoir,-

an electric motor for riving said pump, a switch in the circuit ofsaid motor, said switch being controlled in response to variations in pressure of the fluid in the reservoir, a normally open valve between the reservoir andthe pump, an electromagnet' for closing said valve, said magnet being energized whenever the switchin the motor circuit is closed, and means for retarding the closing of said valve.

12. A fluid pressure system comprising a reservoir, an air compressor supplying said reservoir, an electric motor for driving said air compressor, a switch in a motor circuit, a slow-closing relief valve between the compressor and the reservoir, and an electromagnet for closing said relief valve, said electromagnet being energized whenever the switch in the motor circuit is closed.

In testimony whereof I afiix my signature, in the presence of two witnesses.

CHARLES E. LORD.

Witnesses:

GEO. B. ScHLEY, FRED. J. KINSEY. 

